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"The Adjustable Zener" (or even a 400 mW Audio Amplifier) Experimenters absolutely ♥ this simple but versatile programmable shunt regulator. A single TL431 and a small trimmer potentiometer will replace a whole assortment of zeners. Better yet, since the reference voltage is continuously adjustable from 2.5 to 36 VDC, you will do it with better precision. Never settle for a 'close' fixed zener value again. Afterall, what good is a 1% zener, if it's nominal voltage is 3% off the target voltage you need? Need a simple AUDIO AMPLIFIER? See the 2 examples below. Check the TL431 datasheet. It has many different applications to spur your imagination. This 'zener' can even be used as a microphone / phono amplifier (left) or as a Crystal Radio amplifier using a 32 Ohm speaker without a transformer! Popular TO-92 3-terminal package. Only 3 resistors (not included) are needed to make a precision regulated voltage source. The perfect replacement for even tight tolerance zener diodes. Winner gets (20) pieces. Return to Top Setting the voltage is very easy. Simple algebra is used for the various configurations listed in the datasheet. This device works as a current shunt, just like a zener. It will sink 1 to 100 mA to maintain a precise Positive or Negative voltage from 2.5 to 36 VDC. All you need is the series current limiting resistor (as with zeners) and a voltage divider consisting of two small resistors to program the voltage. * Substitute a trimmer pot for R1/R2 to create a precision adjustable zener diode. * Add a 'pass' transistor for higher load currents. * Need an adjustable, constant current source/sink? This device can do that too, very easily. Datasheet - TI TL431 (572K PDF) Be sure to add us to your Favorites List ! 14 day Non-DOA, Good-on-Arrival Guarantee Untested, but NO JUNK or suspect parts PCB parts are thru-hole, NO SMD/SMT Manufacturers may vary from picture (Variable zeners - 2½ to 36 v (and unique audio amp) was posted and is owned by: Dona Parrish) |
dona.parrish@chicagopartsnetwork.com (Dona Parrish) for more information.
